Historical forest patterns of Oregon's central Coast Range.

摘要

To describe the composition and pattern of unmanaged forest land in the Oregon Central Coast Range, we analysed forest conditions from a random sample of 18 prelogging (1949 and earlier) landscapes. We also compared the amount and variability of oldforest (conifer-dominated stands >53 cm d.b.h.) in the prelogging landscapes with that in current landscapes. Sixty-three percent of the prelogging landscape comprised old forest, approximately 21% of which also had a significant (>20% cover) hardwood component. The proportions of forest types across the 18 prelogging landscapes varied greatly for both early seral stages (cv= 81-194) and hardwoods (cv=127), and varied moderately for old forest (cv= 39). With increasing distance from streams, the amountof hardwood species and nonforest decreased, whereas the amount of seedling/sapling/pole and young conifers increased. The amount of old forest was significantly greater (p<0.002) in prelogging forests than in current landscapes. Old-forest patterns also differed significantly (p<0.015) between prelogging and current landscapes; patch density, coefficient of variation of patch size, edge density, and fragmentation were greater in current landscapes and mean patch size, largest patch size, and core habitat were greater in prelogging forests. Generally, old-forest landscape pattern variables showed a greater range in prelogging landscapes than in current landscapes. Management strategies designed to increase the amount of old forest and the range in landscape patterns would result in a landscape more closely resembling that found prior to intensive logging.